State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding of Zhejiang Province, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, Zhejiang 311400, China.
State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding of Zhejiang Province, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, Zhejiang 311400, China; Fujian Academy of Forestry Sciences, Fuzhou, Fujian 350012, China.
J Hazard Mater. 2024 Dec 5;480:135936. doi: 10.1016/j.jhazmat.2024.135936. Epub 2024 Sep 23.
Cadmium (Cd) is a prominent heavy metal pollutant that inhibits plant growth and poses risks to human health. Sedum plumbizincicola, as a Cd/Zn/Pb hyperaccumulator species, exhibits robust resistance to heavy metals and effective enrichment capacities. In our previous study, overexpressing SpbZIP60 in Arabidopsis enhanced Cd tolerance; however, the underlying the molecular mechanism remains to be elucidated. Here, we identified SpbZIP60 as a representative Cd stress response factor with nuclear localization and transcriptional activation activity. SpbZIP60 underwent conservative splicing in response to endoplasmic reticulum (ER) stress, while its response to Cd stress is independent of the ER stress-mediated unfolded protein response pathway. Overexpression of SpbZIP60 in S. alfredii increased the Cd tolerance and antioxidant activity. Furthermore, SpbZIP60 increased the content of cell wall components and thickened cell wall under Cd stress. Transcriptome analysis indicated a significant enrichment of differentially expressed genes within the phenylpropanoid metabolism pathway. Besides, the binding of SpbZIP60 to the promoter region of SpBglu resulted in the activation of gene expression, thereby enhancing the process of lignin deposition. Collectively, our results elucidated a molecular regulatory model in which SpbZIP60 increased the thickness of the root cell wall to impede Cd entry into the cell, consequently improving Cd tolerance.
镉（Cd）是一种重要的重金属污染物，会抑制植物生长并对人类健康构成威胁。作为一种 Cd/Zn/Pb 超积累物种，Sedum plumbizincicola 对重金属具有很强的抗性和有效的富集能力。在我们之前的研究中，过表达拟南芥中的 SpbZIP60 增强了 Cd 耐受性；然而，其潜在的分子机制仍有待阐明。在这里，我们鉴定出 SpbZIP60 是一种具有核定位和转录激活活性的代表性 Cd 应激响应因子。SpbZIP60 响应内质网（ER）应激时发生保守剪接，而其对 Cd 应激的响应不依赖于 ER 应激介导的未折叠蛋白反应途径。过表达 SpbZIP60 可提高 S. alfredii 的 Cd 耐受性和抗氧化活性。此外，SpbZIP60 在 Cd 胁迫下增加了细胞壁成分的含量并使细胞壁增厚。转录组分析表明，苯丙烷代谢途径中的差异表达基因显著富集。此外，SpbZIP60 与 SpBglu 启动子区域结合，导致基因表达激活，从而增强木质素沉积过程。综上所述，我们的研究结果揭示了一个分子调控模型，即 SpbZIP60 增加了根细胞壁的厚度，阻止了 Cd 进入细胞，从而提高了 Cd 耐受性。
